Figure 2. Generation–detection with unbiased detector junction and simulated response.
(a) Current–voltage characteristics of mesa 4a with N=12 junctions. A sum-gap kink is clearly seen at T<Tc≃81 K. (b) Voltages of the detector mesas 4b and 2a as a function of voltage in the generator 4a. It is seen that Vdet is independent of the generator bias direction. (c) The detector response normalized by the total power in the generator. Characteristic spectroscopic signatures at eVgen/N≃2Δ and 4Δ are seen. (d–f) Simulation of boson generation–detection experiment (s-wave case). (d) Non-equilibrium boson spectra at different voltages in the generator. Relaxation 0<Ω<eVgen/N−2Δ and recombination Ω>2Δ bands are seen. The bands overlap at eVgen/N=4Δ. (e) The number of Ω=2Δ bosons as a function of Vgen. Inset shows the I–V of the generator mesa with N=2 junctions. (f) Normalized detector response Vdet/Pgen∝dRdet/dPgen as a function of generator voltage. A primary peak in response at eVgen/N=2Δ and a secondary dip/upturn at eVgen/N≃4Δ indicate onset of pairbreaking by recombination and relaxation bosons, respectively.